Abstract: An image reading device includes a document tray, a linear conveyance path, a curved conveyance path, a document conveyance device, a scanning device, a length detecting device, an operation device, and a controller. A plurality of conveyance rollers are disposed at a predetermined first interval in the linear conveyance path. In the curved conveyance path, a plurality of conveyance rollers are disposed at a predetermined second interval longer than the first interval. When accepting through the operation device an instruction for conveying an original document through the curved conveyance path, the controller allows conveyance of the original document through the curved conveyance path when a length of the original document detected by the length detecting device is not shorter than the second interval or disallows conveyance of the original document through the curved conveyance path when the detected length of the original document is shorter than the second interval.

Abstract: An image reading apparatus includes a document tray, a common transport route, a curved transport route, a linear transport route, a switching device, a document transport device, a first image sensor, a second image sensor, a trailing edge detector, a multi feed detector, a leading edge detector, and a controller. The controller determines a length of the document in the transport direction, on a basis of a time point that the leading edge detector has detected the leading edge of the document, a time point that the trailing edge detector has detected the trailing edge of the document, and a time point that a detection status of the multi feed detector has been switched to a non-detection state, and guides the document to the curved transport route or the linear transport route from the common transport route, according to the length of the document, by controlling the switching device.